FRIDAY, May 3 (HealthDay News) -- Young students are more likely to choose healthier school lunches if they can preorder them, away from the temptations of the sights and aromas of food in the lunchroom, a new study finds.

The research included nearly 300 students at two elementary schools in upstate New York. Over a four-week period, the students used an electronic system to preorder their lunch's main dish.

About 29 percent of the students selected the healthier entree when they were able to preorder, but that number dropped to about 15 percent when preordering was not available.

Students were also 48 percent less likely to select a healthier main dish and 21 percent more likely to chose a less healthy main dish when they made their choice in the lunch line instead of preordering, the researchers added.

The findings appear in a research letter published online May 3 in the journal JAMA Pediatrics.

The findings "demonstrate how a simple environmental change -- preordering -- can prompt children to choose healthier food," concluded Andrew Hanks, of Cornell University, and colleagues.

How does preordering help kids make healthier choices? According to the researchers, "preordering could preempt hunger-based, spontaneous selections and eliminate the sensory cues -- evocative smells and sights -- that lead to less healthy choices."

Hanks and his team say the preordering system used in the study was computer-based, but "paper-based systems are easy, inexpensive, and an immediately implementable alternative" for cash-strapped schools.

The bottom line, they say: "A smarter lunchroom is not confined to the space between the cafeteria walls."